The `radicle-cob` crate provides a feature flag, `stable-commit-ids` to allow
for `Oid`s to remain stable for testing by always using the same author and
timestamp when creating commits.
This can be an issue when it interplays with COB related tests that are relying
on the ordering for the DAG walk. If the `Oid` values change and get re-ordered
then the test will fail. The DAG for COBs are now ordered via the `Oid` and
`Timestamp`.
In this change, a global timestamp is introduced that is initialised
per thread. The value is read, via `read_timestamp`, and can be
advanced using `with_advanced_timestamp` – while performing an action
that creates a new commit.
Lorenz Leutgeb
Fintan Halpenny